Ans. (b). has a genome made of RNA.
Retroviruses are viruses with RNA molecules as their genome. They insert a copy of their RNA genome into the host cell DNA and change the cell genome. These viruses are generally known as single-stranded positive-sense (+ strand) RNA viruses.
Examples: Human immunodeficiency virus and hepatitis B virus.
Thus, the correct answer is option (b).
Ans. (a). through reproduction of the host cell.
Lysogenic life cycle is a virus reproductive cycle that involves integration of viral nucleic acid into host's genome or formation of a replicon in host's cytoplasm.
The host cells (bacterial cells) remain alive and reproduce normally, so thus, viruses reproduce through the reproduction of host (bacterial cells).
Thus, the correct answer is option (a).